.housing-group {
    display: flex;
    flex-wrap: wrap;
}

.housing {
    font-weight: bold;    
    flex: 1 1 45%;    
}

.housing:nth-child(odd) {
    margin-left: 0px;
}

.housing:nth-child(even) {
    margin-right: 0px;
}

@media(min-width: 733px){
    .housing {
        flex: 1 1 20%; 
        margin: 15px 7.5px;
    }

    .housing:nth-child(odd), .housing:nth-child(even) {
        /* reset */
        margin: 0px 7.5px 15px 7.5px;
    }    

    .housing:first-child {
        margin-left: 0px;
    }
    
    .housing:last-child {
        margin-right: 0px;
    }
}